Rapid Synthesis of D‐A′‐π‐A Dyes through a One‐Pot Three‐Component Suzuki–Miyaura Coupling and an Evaluation of their Photovoltaic Properties for Use in Dye‐Sensitized Solar Cells

Twenty‐four D‐A′–π‐A dyes were rapidly synthesized through a one‐pot three‐component Suzuki–Miyaura coupling reaction, which was assisted by microwave irradiation. We measured the absorption spectra, electrochemical properties, and solar‐cell performance of all the synthesized dyes. The D5 πA4 dye contained our originally designed rigid and nonplanar donor and exerted the highest efficiency at 5.4 %. The short‐circuit current (J_sc) was the most important parameter for the conversion efficiency (η) in the case of the organic D‐A′‐π‐A dyes. Optimal ranges for the D‐A′‐π‐A dyes were observed for high values of J_sc/λ_max at λ=560–620 nm, an optical‐absorption edge of λ=690–790 nm, and E_HOMO and E_LUMO values of <1.14 and ?0.56 to ?0.76 V, respectively.     

Rapid Synthesis of Thiophene‐Based,Organic Dyes for Dye‐Sensitized Solar Cells (DSSCs) by a One‐Pot,Four‐Component Coupling Approach

This one‐pot, four‐component coupling approach (Suzuki–Miyaura coupling/C?H direct arylation/Knoevenagel condensation) was developed for the rapid synthesis of thiophene‐based organic dyes for dye‐sensitized solar cells (DSSCs). Seven thiophene‐based, organic dyes of various donor structures with/without the use of a 3,4‐ethylenedioxythiophene (EDOT) moiety were successfully synthesized in good yields based on a readily available thiophene boronic acid pinacol ester scaffold (one‐pot, 3‐step, 35–61 %). Evaluation of the photovoltaic properties of the solar cells that were prepared using the synthesized dyes revealed that the introduction of an EDOT structure beside a cyanoacrylic acid moiety improved the short‐circuit current (J_sc) while decreasing the fill factor (FF). The donor structure significantly influenced the open‐circuit voltage (V_oc), the FF, and the power conversion efficiency (PCE). The use of a n‐hexyloxyphenyl amine donor, and our originally developed, rigid, and nonplanar donor, both promoted good cell performance (η=5.2–5.6 %).     

Stereoselective synthesis of contiguous THF–THF and THF–THP units via Pd-catalyzed tandem reaction with 1,3-chirality transfer

The Pd^II-catalyzed tandem cyclization of chiral allylic alcohols possessing an internal epoxide and a terminal alcohol provided a contiguous THF–THP and THF–THP ring units stereospecifically. The cyclizations take place via a 5-exo-tet-5-exo-trig mode, however, the cyclization of methyl substituted epoxy diols proceeded via 6-endo-tet-6-exo-trig fashion in a part to construct the oxygen-fused THP–THP ring. The different reaction rates of precursors, which are different stereochemistry at allylic alcohol have been elucidated.     

Chiral porphyrin dimer with a macrocyclic cavity for intercalation of aromatic guests

Chiral diporphyrin receptor 1, which has a macrocyclic cavity to sandwich aromatic guest molecules via double π-π stacking interactions, enabled the naked-eye detection of an aromatic explosive as well as chiral discrimination in NMR.     

A touch-and-go lipid wrapping technique in microfluidic channels for rapid fabrication of multifunctional envelope-type gene delivery nanodevices

Multifunctional envelope-type gene delivery nanodevices (MENDs) are promising non-viral vectors for gene therapy. Though MENDs remain strong in prolonged exposure to blood circulation, have low immunogenic response, and are suitable for gene targeting, their fabrication requires labor-intensive processes. In this work, a novel approach has been developed for rapid fabrication of MENDs by a touch-and-go lipid wrapping technique in a polydimethylsiloxane (PDMS)/glass microfluidic device. The MEND was fabricated on a glass substrate by introduction of a condensed plasmid DNA core into microfluidic channels that have multiple lipid bilayer films. The principle of the MEND fabrication in the microfluidic channels is based on electrostatic interaction between the condensed plasmid DNA cores and the coated lipid bilayer films. The constructed MEND was collected off-chip and characterized by dynamic light scattering. The MEND was constructed within 5 min with a narrow size distribution centered around 200 nm diameter particles. The size of the MEND showed strong dependence on flow velocity of the condensed plasmid DNA core in the microfluidic channels, and thus, could be controlled to provide the optimal size for medical applications. This approach was also proved possible for fabrication of a MEND in multiple channels at the same time. This on-chip fabrication of the MEND was very simple, rapid, convenient, and cost-effective compared with conventional methods. Our results strongly indicated that MENDs fabricated with our microfluidic device have a good potential for medical use. Moreover, MENDs fabricated by this microfluidic device have a great potential for clinical use because the devices are autoclavable and all the fabrication steps can be completed inside closed microfluidic channels without any external contamination.     

Total Syntheses of (−)‐Strictosidine and Related Indole Alkaloid Glycosides

A collective synthesis of glycosylated monoterpenoid indole alkaloids is reported. A highly diastereoselective Pictet–Spengler reaction with α‐cyanotryptamine and secologanin tetraacetate as substrates, followed by a reductive decyanation reaction, was developed for the synthesis of (?)‐strictosidine, which is an important intermediate in biosynthesis. This two‐step chemical method was established as an alternative to the biosynthetically employed strictosidine synthase. Furthermore, after carrying out chemical and computational studies, a transition state for induction of diastereoselectivity in our newly discovered Pictet–Spengler reaction is proposed. Having achieved the first enantioselective total synthesis of (?)‐strictosidine in just 10 steps, subsequent bioinspired transformations resulted in the concise total syntheses of (?)‐strictosamide, (?)‐neonaucleoside A, (?)‐cymoside, and (?)‐3α‐dihydrocadambine.     

Design of ultra compact all-optical XOR and AND logic gates with low power consumption

We propose a novel ultra-compact all-optical XOR and AND logic gates without using nonlinear optics. In order to realize these devices, we adopt photonic crystal waveguides (PCWs) based on multi-mode interference devices. Numerical results show that the operating bandwidth of the ON to OFF logic-level contrast ratio of not less than 6.79 dB is 35 nm for XOR logic gate and 9 nm for AND logic gate. Proposed logic gates have the potential to be key components for an optical packet switching system due to their small feature sizes and low power consumption.     

Relaxation Behaviors of Free Radicals From γ-Irradiated Black Pepper Using Pulsed EPR Spectroscopy

Using electron paramagnetic resonance (EPR) spectroscopy, we revealed the relaxation behaviors of free radicals in γ-irradiated black pepper. Upon γ-irradiation, typical doublet peaks were detected. Relaxation times (T ₁ and T ₂) were observed using pulsed EPR. We found that T ₁ and T ₂ values varied with the γ-irradiation dose levels and these values showed a dependence on the dose level of the γ-irradiation treatment.